Commit 66b333b3 authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Phil Elwell
Browse files

pwm: Send a uevent on the pwmchip device upon channel sysfs (un)export 

This patch sends a uevent (KOBJ_CHANGE) on the pwmchipN device,
everytime a pwmX channel has been exported/unexported via sysfs. This
allows udev to implement rules on such events, like:

SUBSYSTEM=="pwm*", PROGRAM="/bin/sh -c '\
        chown -R root:gpio /sys/class/pwm && chmod -R 770 /sys/class/pwm;\
        chown -R root:gpio
/sys/devices/platform/soc/*.pwm/pwm/pwmchip* && chmod -R 770
/sys/devices/platform/soc/*.pwm/pwm/pwmchip*\
'"

This is a replacement patch for commit 7e5d1fd7 ("pwm: Set class for
exported channels in sysfs"), see [1].

basic testing:
$ udevadm monitor --environment &
$ echo 0 > /sys/class/pwm/pwmchip0/export
KERNEL[197.321736] change   /devices/.../pwm/pwmchip0 (pwm)
ACTION=change
DEVPATH=/devices/.../pwm/pwmchip0
EXPORT=pwm0
SEQNUM=2045
SUBSYSTEM=pwm

[1] https://lkml.org/lkml/2018/9/25/713



Signed-off-by: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Tested-by: default avatarGottfried Haider <gottfried.haider@gmail.com>
Tested-by: default avatarMichal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 18d8ed01

drivers/pwm/sysfs.c

+11 −0
Original line number Diff line number Diff line
@@ -249,6 +249,7 @@ static void pwm_export_release(struct device *child) 
static int pwm_export_child(struct device *parent, struct pwm_device *pwm)

{

	struct pwm_export *export;

	char *pwm_prop[2];

	int ret;



	if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
@@ -275,6 +276,10 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) 
		kfree(export);

		return ret;

	}

	pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);

	pwm_prop[1] = NULL;

	kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);

	kfree(pwm_prop[0]);



	return 0;

}
@@ -287,6 +292,7 @@ static int pwm_unexport_match(struct device *child, void *data) 
static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)

{

	struct device *child;

	char *pwm_prop[2];



	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))

		return -ENODEV;
@@ -295,6 +301,11 @@ static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) 
	if (!child)

		return -ENODEV;



	pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);

	pwm_prop[1] = NULL;

	kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);

	kfree(pwm_prop[0]);



	/* for device_find_child() */

	put_device(child);

	device_unregister(child);